Open street map (OSM) tags are annotations like
amenity=watering_place. It is very important to document exactly what
such a tag and such a tag value means. Only then data can become real
information.

They looked at the presets for tags in the various OSM editors. There’s also
Wikidata, OSMonto and the OSM semantic network. And.... the OSM wiki. The Wiki
is the most important place.

They tried to visualize the information in the wiki. Which is a hard job
because the data is hardly machine-readable.

A possible visualization is for instance a tag cloud, to get a visual
impression. And they made an interactive tool to show the historical
development in tags. And a comparison between tags in the wiki and tags in the
actual OSM database.

geopedia shows the wikipedia entries around a
location. You get a clickable map.

He took special care to support various languages. In Germany, you can
get the best/most results in the german wikipedia. Likewise, for other
languages/countries. There’s a button to switch between languages/wikipedias.